1800-2100 rpms for an idle on these. Depends on if it's warmed dup or not. warmed up it should be around 1800 rpms. I know it sounds high, but its a single with a tiny piston and weight. Needs that inertia to stay running. A car idles around 500-1100 rpms because it has a lot more weight to keep it spinning. My motorcycle idles around 1100-1300 rpms( 2000 rpms when cold and choked), but it's also like 7 CG's in displacement, with big counter weights.